Baffle Step Phenomenon Bafflement

[Steve O]

I've been reading up on the baffle step phenomenon and the means of compensating for it in xover design. References I've found so far generally state that the situation occurs because the a driver appears to radiate into a sphere at low frequencies. At higher frequencies largely dependent upon baffle dimensions, the apparent driver radiation pattern transitions into a hemisphere. So far, so good. However, these references also go on to state that the apparent increase in level above the transition region is 6dB but they don't explain why 6dB. Intuitively, it seems that 3dB would be the increase because energy is radiated into half the original volume, thus apparent power level is doubled or +3dB.

Anyone have any insights as to what I'm missing here? I'd like to understand this at a basic level...basic meaning the elementary physics of the phenomenon.

TIA

[Zilch]

Well, you've stumped the Zilchster, again.

[Ray's gonna know, probably.... :yes: ]

It's 4-Pi to 1-Pi, actually, sitting on the floor, no?

2-Pi would be hanging on the wall.

The compensation is usually less than 6 dB....

[Jim Shearer]

From my limited experience in building speakers using single full range drivers, I find the correction to be around 4 dB. That's to get the sound I want, not flat response in an anechoic chamber.

Cheers, Jim

[GordonW]

Well, you've stumped the Zilchster, again.

[Ray's gonna know, probably.... :yes: ]

It's 4-Pi to 1-Pi, actually, sitting on the floor, no?

2-Pi would be hanging on the wall.

The compensation is usually less than 6 dB....

Actually, it'd be 2-pi to 1-pi on the floor. :D

Free-space, it'd be 4-pi to 2-pi...

On the wall, it'd be 2 pi with a slight delay at LF, to 2pi without the delay...

Regards,
Gordon.

[Zilch]

Yup, on the floor and against the wall, it's 4-Pi to 1-Pi, and that's how I get Steve's 6 dB.

[Maybe.... :p: ]